1. Field of the Invention
The invention relates to the purification of water and to obtaining water which is apyrogenic and freed from essentially organic substances capable of interfering with research of a biological, physico-chemical, or physical phenomenon or spoiling medico-sanitary practice.
2. Description of the Prior Art
Numerous installations are already known which enable the manufacture of distilled water on a larger or smaller scale. Complete plants enable, for example, the desalination of sea water by distillation of the latter. Laboratory equipment produces deionised distilled water suitable in numerous applications.
However, known technology goes not permit obtaining water which is essentially pure and, in particular, free of previously-noted contaminants as defined above. The latter are entrained during distillation of water, of which the steam, on condensation, supplies so-called purified water, which still contains a certain amount of substances carried through the distillation. It is desirable to obtain an apyrogenic water, free of essentially organic contaminants and of ions and having a biological innocuousness, notably for very exacting requirements.
Thus the invention relates to improvements in the general technique of water distillation, for the purification of the latter.
By way of document illustrating the state of the art, GB Pat. No. 4897 AD 1912 may be mentioned. This patent relates to a small portable device for distilling and sterilising liquids, such as water. It is proposed to destroy bacteria detained in water by causing the steam to pass, before condensation, into a superheating zone constituted by a simple tube connecting the still to a condensing receiver. Such a device does not permit practically complete removal of the organic substances from the water. Simple superheating by means of a flame or of a resistance around the tube in which the steam flows is not sufficient to remove organic substances. This patent does not describe any means for rendering the heating homogeneous in the superheated zone, nor the possibility of regulating, in a controlled manner, the dwell time of the steam in this zone.
It is an object of the present invention, on the other hand, to remove almost completely, the organic substances contained in the water. Organic impurities are the most troublesome contaminants in certain applications, for example in molecular biology or in genetics, since, by reason of the precision of modern biology, the least organic impurity contained in the aqueous medium, results in errors and false results. The very particular needs of biology require the utilisation of water free of organic impurities. Water which is presently available and reputed to be very pure is, mostly, characterised by its properties of conductivity or of pH, but these values are of no help in the problem resolved by the invention, considering that organic substances are non-conducting. Water meeting the most exacting requirements as regards conductivity is inept for biological requirements.
At the present time, for such water, water from natural sources is used, or it is necessary to distill water several times in quartz, after having previously treated it with potassium permangenate. This bidistillation is relatively expensive, but it does not provide a completely satisfactory water for biological needs.
Another known process for purifying water consists of freeing it from ions that it contains by passing it through diaphragms or filters of very low porosity. Specialists who work in the biological field, for example in molecular biology, for in vitro syntheses know that water obtained in this manner is not suitable for their requirements. It still contains too high an amount of organic residues which generally reach some milligrams per liter.